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Research & Scholarship

Current Research and Scholarly Interests

Dr. Michael Bellino joined the Stanford University Medical Center in 2001 after completing his post-doctoral fellowship in Hip and Pelvis Reconstruction with Dr. Joel Matta at Good Samaritan Hospital in Los Angeles.Dr. Bellino also serves as a Clinical Associate Professor of Orthopaedic Surgery with specialty interest in hip and pelvis reconstruction. His areas of clinical expertise include: pelvis and acetabulum fractures, periarticular and long bone fractures, malunions and nonunions, hip arthritis, hip dysplasia, and femoro-acetabular impingement. His research interests focus on anatomy and biomechanics of the hip and pelvis as well as surgical treatments for disorders of the hip.Dr. Bellino received his undergraduate degree in Zoology from the University of Massachusetts, Amherst and his medical degree from New York Medical College. He completed his orthopaedic residency at the University of California, Davis. Dr Bellino is also Chairman of Quality Assurance, Department of Orthopaedic Surgery and Co-Chairman of Quality Assurance Trauma Division Stanford University School of Medicine. He is an active member of the American Academy of Orthopaedic Surgeons and Orthopaedic Trauma Association. He is AO (Arbeitsgemeinschaft fur Osteosynthesefragen) Faculty. He was the recent recipient of Saul Halpern, MD Orthopaedic Educator Award Department of Orthopaedic Surgery Stanford University School of Medicine.He has authored and co-authored book chapters and journal articles published in areas of pelvis biomechanics and acetabular fractures. He has given numerous invited national and international lectureships.

All Publications

Abstract

Degenerative changes of the sacroiliac joint have been implicated as a cause of lower back pain in adults. The purpose of this study was to determine the prevalence of sacroiliac joint degeneration in asymptomatic patients.Five hundred consecutive pelvic computed tomography (CT) scans, made at a tertiary-care medical center, of patients with no history of pain in the lower back or pelvic girdle were retrospectively reviewed and analyzed for degenerative changes of the sacroiliac joint. After exclusion criteria were applied, 373 CT scans (746 sacroiliac joints) were evaluated for degenerative changes. Regression analysis was used to determine the association between age and the degree of sacroiliac joint degeneration.The prevalence of sacroiliac joint degeneration was 65.1%, with substantial degeneration occurring in 30.5% of asymptomatic subjects. The prevalence steadily increased with age, with 91% of subjects in the ninth decade of life displaying degenerative changes.Radiographic evidence of sacroiliac joint degeneration is highly prevalent in the asymptomatic population and is associated with age. Caution must be exercised when attributing lower back or pelvic girdle pain to sacroiliac joint degeneration seen on imaging.Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Abstract

Reduced limb length discrepancy and more accurate cup positioning are purported benefits of using fluoroscopy for total hip arthroplasty (THA). The authors compared limb length discrepancy and cup position in 200 patients (group I, posterior approach without fluoroscopy; group II, anterior supine approach with fluoroscopy) who underwent primary THA. Mean limb length discrepancy was 2.7 mm (SD, 5.2 mm; range, -9.8 to 20.9 mm) and 0.7 mm (SD, 3.7 mm; range, -11.8 to 10.5 mm) for groups I and II, respectively (P=.002). In group I, 7% of hips had limb length discrepancy greater than 1 cm compared with 3% in group II. Mean cup inclination measured 40.8° (SD, 5.0°; range, 26.1°-53.7°) in group I and 43.4° (SD, 5.6°; range, 31.3°-55.9°) in group II (P=.008). In group I, 96% of cups had inclination within 10° of the mean compared with 92% in group II (P=.24). Mean anteversion measured 35.3° (SD, 7.1°; range, 17.8°-60.7°) in group I and 25.9° (SD, 8.2°; range, 1.5°-44.8°) in group II (P=.0001). In group I, 87% of hips exhibited anteversion within 10° of the mean compared with 76% in group II (P=.045). Although the anterior approach with intraoperative fluoroscopy reduced mean limb length discrepancy, the clinical significance of this reduction is unclear. Fluoroscopy reduced the incidence of limb length discrepancy greater than 1 cm. However, the use of fluoroscopy did not help to improve the precision of cup positioning.

Abstract

To report hip synovial fluid cytokine concentrations in hips with and without radiographic arthritis.Patients with no arthritis (Tonnis grade 0) and patients with Tonnis grade 2 or greater hip osteoarthritis (OA) were identified from patients undergoing either hip arthroscopy or arthroplasty. Synovial fluid was collected at the time of portal establishment for those undergoing hip arthroscopy and prior to arthrotomy for the arthroplasty group. Analytes included fibronectin-aggrecan complex (FAC) as well as a standard 12 cytokine array. Variables recorded were Tonnis grade, centre-edge angle of Wiberg, as well as labrum and cartilage pathology for the hip arthroscopy cohort. A priori power analysis was conducted, and a Mann-Whitney U test and regression analyses were used with an alpha value of 0.05 set as significant.Thirty-four patients were included (17 arthroplasty, 17 arthroscopy). FAC was the only analyte to show a significant difference between those with and without OA (p

Abstract

Surgical techniques and fixation strategies for the treatment of unstable posterior pelvic ring injuries continue to evolve. The safety of the posterior surgical approach in particular has been questioned due to historically high rates of wound related complications. More contemporary studies have shown lower infection rates, however concern still persists. These concerns for infection and wound necrosis have led, in part, to increased interest in closed reduction and percutaneous fixation for treatment of these injuries but an open posterior approach remains the optimal strategy in some injury patterns. We describe herein a modified posterior approach to the pelvis designed to minimize wound related complications and present our clinical results demonstrating wound complication rates consistent with contemporary publications.

Abstract

To compare clinical and radiological outcome between acetabular fractures with marginal impaction that were treated with either cancellous bone graft (CBG) or tricalcium phosphate cement (TPC) as bone void filler.Retrospective study.Forty-three patients with acetabular fractures with marginal impaction.Eighteen patients received cancellous bone graft and 25 patients received tricalcium phosphate cement as bone void filler.Clinical outcome was assessed using the Merle d'Aubigne score and Short-form-36. Radiographs were evaluated for postoperative reduction, arthritis grade and development of heterotopic ossification.Forty-three patients met the inclusion criteria. There was no significant difference in the demographics, laterality, fracture type, associated injuries, surgical approach and postoperative quality of reduction between the groups. At final follow-up, a significantly higher number of patients in the cancellous bone graft group exhibited signs of moderate to severe post-traumatic arthritis (CBG: 6 (33%) vs. TPC: 4 (20%), p=0.007) and required a total hip arthroplasty (CBG: 4 (22.2%) vs. TPC: 1 (5%), p=0.08). There was no significant difference between the two groups in the SF-36 score and the modified Merle d'Aubigne score.Patients with acetabular fractures with marginal impaction treated with tricalcium phosphate cement exhibit a significantly lower incidence of post-traumatic arthritis when compared to patients treated with cancellous bone graft.III.

Abstract

Postoperative heterotopic ossification (HO) about the elbow may occur after surgical fixation of fractures and can contribute to dysfunction. Factors associated with HO formation after surgical fixation of elbow trauma are not well understood.All patients who underwent surgery for elbow trauma at our institution from October 2001 through August 2010 were retrospectively reviewed. Patients with prior injury or deformity to the involved elbow were excluded. Demographic data; fracture type; surgical treatment; and presence, location, and size of HO were recorded. The Fisher exact test, ?(2) test, and multivariate logistic regression were used with an ? value of .05 used for significance.A total of 159 patients were identified, with 89 (37 men and 52 women) meeting inclusion and exclusion criteria. The mean age was 54.4 years (range, 18-90 years), and the mean follow-up time was 180 days. Age, male gender, lateral collateral ligament repair, and dual-incision approach were not associated with increased ectopic bone formation. Distal humeral fractures were a significant predictor of heterotopic bone. In patients in whom HO ultimately developed, it was visible on radiographs obtained 2 weeks postoperatively in 86% of cases.This investigation found predictors for the development of HO after surgical fixation of intra-articular elbow fractures. Furthermore, HO went on to develop at the time of final follow-up in only 14% of patients without HO on radiographs obtained 2 weeks postoperatively. This may suggest that absence of HO on radiographs obtained 2 weeks postoperatively may predict a more favorable outcome.

Abstract

No standard criteria exist for diagnosing fracture nonunion, and studies suggest that assessment of fracture healing varies among orthopaedic surgeons. This variability can be problematic in both clinical and orthopaedic trauma research settings. An understanding of risk factors for nonunion and of diagnostic tests used to assess fracture healing can facilitate a systematic approach to evaluation and management. Risk factors for nonunion include medical comorbidities, age, and the characteristics of the injury. The method of fracture management also influences healing. Comprehensive evaluation includes an assessment of the patient's symptoms, signs, and immune and endocrine status as well as the biologic capacity of the fracture, presence of infection, and quality of reduction and fixation. Diagnostic tests include plain radiography, CT, ultrasonography, fluoroscopy, bone scan, MRI, and several laboratory tests, including assays for bone turnover markers in the peripheral circulation. A systematic approach to evaluating fracture union can help surgeons determine the timing and nature of interventions.

Abstract

The objective of this study was to determine whether one can achieve stable fixation of a two column (transverse) acetabular fracture by only fixing a single column with a locking plate and unicortical locking screws. We hypothesized that a locking plate applied to the anterior column of a transverse acetabular fracture would create a construct that is more rigid than a non-locking plate, and that this construct would be biomechanically comparable to two column fixation.Using urethane foam models of the pelvis, we simulated transverse acetabular fractures and stabilized them with 1) an anterior column plate with bicortical screws, 2) an anterior locking plate with unicortical screws, 3) an anterior plate and posterior column lag screw, and 4) a posterior plate with an anterior column lag screw. These constructs were mechanically loaded on a servohydraulic material testing machine. Construct stiffness and fracture displacement were measured.We found that two column fixation is 54% stiffer than a single column fixation with a conventional plate with bicortical screws. There was no significant difference between fixation with an anterior column locking plate with unicortical screws and an anterior plate with posterior column lag screw. We detected a non-significant trend towards more stiffness for the anterior locking plate compared to the anterior non-locking plate.In conclusion, a locking plate construct of the anterior column provides less stability than a traditional both column construct with posterior plate and anterior column lag screw. However, the locking construct offers greater strength than a non-locking, bicortical construct, which in addition often requires extensive contouring and its application is oftentimes accompanied by the risk of neurovascular damage.

Abstract

The Emergency Medical Treatment and Active Labor Act (EMTALA) effectively requires Level I trauma centers (TC) to accept all transfers for a higher level of care if capacity exists. We hypothesized that EMTALA would burden a Level I TC by a selective referral of a poor payer mix of primarily nonoperative patients.All transfer calls (December 2003 and September 2005) to our Level I TC are handled by a dedicated transfer center. Calls were reviewed for age, surgical service requested, and outcome of request. The trauma registry was queried to compare Injury Severity Scale (ISS) score, hospital stay (LOS), operations, mortality, and payer status for transfer and primary catchment patients.In all, 821 calls were received; 77 calls were cancelled by the referring hospital and 52 were for consultation only. Of the 692 transfer requests, 534 (77%) were accepted, 134 (19%) were denied for no capacity, and only 24 (4%) were declined by TC as not clinically indicated. Transferred patients were younger (32.0 +/- 1.49 versus 38.9 +/- 0.51, p < 0.05), had similar ISS scores (13.6 +/- 0.62 versus 13.7 +/- 0.26) and LOS (7.0 +/- 0.70 versus 7.4 +/- 0.25), but were somewhat more likely to require an operation than direct admissions (58% versus 51%, p < 0.05). Although trauma (24%) and neurosurgery (24%) were the most commonly requested services, followed by orthopedics (20%), orthopedics accounted for 60% of operations on transferred patients compared with 10% to 13% for trauma and neurosurgery (mostly spine). There was no difference in the payer status of transfer and direct admit patients.Contrary to our assumptions, EMTALA patients had an identical payer mix and similar operative need compared with our primary catchment patients. They do represent a large additional patient load (20% of admissions) and differentially impact specialists, mostly operative for orthopedics and complex nonoperative care for trauma and neurosurgery. These data suggest that the primary motivations for transfer are specialist availability and complexity of care rather than financial concerns. As TCs provide backup specialty call coverage for a wide geographic area, this further supports the need for trauma systems development.